Christopher Mulligan, 26, was reported missing from Hebden Bridge on Thursday, May 25.
He is described as white, 5ft 6ins tall, with short mousy brown hair and a short brown beard. He was last seen wearing black trainers, grey tracksuit bottoms and a grey hoody with red writing across the chest.
Detective Inspector Gary Stephenson, of Calderdale CID, said: “I am urgently appealing to anyone who believes they may have seen Christopher or knows his whereabouts to contact the police as soon as possible.
“It has been nearly two weeks since Christopher was last seen and his friends and family are extremely worried for his welfare. Our investigation remains ongoing and we have officers conducting extensive enquiries to locate him.
“It is believed that Christopher does have links to Rochdale and Burnley areas and he has previously travelled there.”
Anyone with any information on Christopher’s whereabouts or if they believe they have seen him is asked to contact Calderdale CID immediately via 101 quoting log number *702 of 25/05.